PROJECT SUMMARY A difficulty in the development of effective treatments against pancreatic cancer is heterogeneity within and between tumors; a subset of cancer cells, rather than all cells in a tumor, is responsible for the behaviors of invasiveness and resistance to death. Drugs that act on the aggressive subpopulations promise to be more effective than drugs that act on the bulk of a tumor, but research to identify such drugs is hampered by the lack of biomarkers to detect, isolate, and study the aggressive subpopulations. The goal of this project is to identify biomarkers of aggressive subpopulations of pancreatic cancer cells. We hypothesize that distinct subtypes of pancreatic cancer cells exist, and that they differ in their invasiveness and resistance to death. We found support for this hypothesis in previous research through the identification of glycan biomarkers of subpopulations of cancer cells with differences in molecular characteristics and behaviors. We will build on the previous results to fully test the possibility that specific glycan markers can be used for detecting subtypes of cancer cells. We posit that aggressive subtypes will be associated with poor outcomes, and that they will display high invasiveness and resistance to death in model systems. To enable a complete evaluation of the candidate markers, we will employ valuable tissue resources such as primary tumors, patient-derived xenografts, and tumor organoids, and we will apply unique and powerful experimental systems?multimarker immunofluorescence and MALDI glycan imaging. Biomarkers that identify the aggressive subtypes of pancreatic cancer cells could pave the way for the development of truly effective therapies. They would provide a way to determine which model systems, or which cells within the models, are the important ones to target, and they would provide companion diagnostics to guide and monitor the use of the targeted therapies. Drugs arising from such research would, for the first time, strike at the critical point?the subset of cells giving rise to the lethal nature of the disease. We are in a good position to produce significant results given the leads from previous research, our technologies and resources, and the team of clinical, technological, and statistical experts.